On Wed, Jan 21, 2026 at 11:41:48AM +0100, Christian König wrote: > On 1/20/26 21:44, Matthew Brost wrote: > > On Tue, Jan 20, 2026 at 04:07:06PM +0200, Leon Romanovsky wrote: > >> From: Leon Romanovsky <[email protected]> > >> > >> dma-buf invalidation is performed asynchronously by hardware, so VFIO must > >> wait until all affected objects have been fully invalidated. > >> > >> Fixes: 5d74781ebc86 ("vfio/pci: Add dma-buf export support for MMIO > >> regions") > >> Signed-off-by: Leon Romanovsky <[email protected]> > >> --- > >> drivers/vfio/pci/vfio_pci_dmabuf.c | 5 +++++ > >> 1 file changed, 5 insertions(+) > >> > >> diff --git a/drivers/vfio/pci/vfio_pci_dmabuf.c > >> b/drivers/vfio/pci/vfio_pci_dmabuf.c > >> index d4d0f7d08c53..33bc6a1909dd 100644 > >> --- a/drivers/vfio/pci/vfio_pci_dmabuf.c > >> +++ b/drivers/vfio/pci/vfio_pci_dmabuf.c > >> @@ -321,6 +321,9 @@ void vfio_pci_dma_buf_move(struct vfio_pci_core_device > >> *vdev, bool revoked) > >> dma_resv_lock(priv->dmabuf->resv, NULL); > >> priv->revoked = revoked; > >> dma_buf_move_notify(priv->dmabuf); > >> + dma_resv_wait_timeout(priv->dmabuf->resv, > >> + DMA_RESV_USAGE_KERNEL, false, > >> + MAX_SCHEDULE_TIMEOUT); > > > > Should we explicitly call out in the dma_buf_move_notify() / > > invalidate_mappings kernel-doc that KERNEL slots are the mechanism > > for communicating asynchronous dma_buf_move_notify / > > invalidate_mappings events via fences? > > Oh, I missed that! And no that is not correct. > > This should be DMA_RESV_USAGE_BOOKKEEP so that we wait for everything.
Will change. > > Regards, > Christian. > > > > > Yes, this is probably implied, but it wouldn’t hurt to state this > > explicitly as part of the cross-driver contract. > > > > Here is what we have now: > > > > * - Dynamic importers should set fences for any access that they can't > > * disable immediately from their > > &dma_buf_attach_ops.invalidate_mappings > > * callback. > > > > Matt > > > >> dma_resv_unlock(priv->dmabuf->resv); > >> } > >> fput(priv->dmabuf->file); > >> @@ -342,6 +345,8 @@ void vfio_pci_dma_buf_cleanup(struct > >> vfio_pci_core_device *vdev) > >> priv->vdev = NULL; > >> priv->revoked = true; > >> dma_buf_move_notify(priv->dmabuf); > >> + dma_resv_wait_timeout(priv->dmabuf->resv, DMA_RESV_USAGE_KERNEL, > >> + false, MAX_SCHEDULE_TIMEOUT); > >> dma_resv_unlock(priv->dmabuf->resv); > >> vfio_device_put_registration(&vdev->vdev); > >> fput(priv->dmabuf->file); > >> > >> -- > >> 2.52.0 > >> > >
